Physics in free fall

Dropping supercold atoms may prove useful for understanding general relativity

In an experiment that puts the good old-fashioned egg drop to shame, European physicists dropped a small blob of ultracold atoms down a 146-meter-tall shaft. The result: no yolk on their face.

In the new study, researchers created a cloud of about 10,000 ultracold rubidium atoms, so still and chilly that the atoms fused into a quirky quantum object called a Bose-Einstein condensate.